Apparatus for thermally conditioning articles and the like



June 25, 1968 w, CUNE, 3,389,478

APPARATUS FOR THERMALLY CONDITIONING ARTICLES AND THE LIKE Filed March 3, 1966 2 Sheets-Sheet 1 IN VENTOR. Les/la W. Cline w/r/vEss -w ATTORNEY June 25, 1968 w, m 3,389,478

APPARATUS FOR THERMAL-LY CONDITIONING ARTICLES AND THE LIKE Filed March 3. 1966 2 Sheets-Sheet 2 la INVENTOR.

Leslie W. Cline lo BY WITNESS 48 Q84 W A TORNEY United States Patent 0 3,389,478 APPARATUS FOR THERMALLY CONDITIONING ARTICLES AND THE LIKE Leslie W. Cline, Brockton, Mass, assignor, by rnesne assignments, to Anderson Electric Corporation, Leeds, Ala., a corporation of Alabama Filed Mar. 3, 1966, Ser. No. 531,385 2 Claims. (Cl. 34-216) ABSTRACT OF THE DISCLOSURE A heat shrink tunnel is herein disclosed for heat shrinking plastic film wrappers about articles and the like. The tunnel has a pair of vertically spaced plenum chambers defining a passage therebetween for the passage of the articles. The upper plenum chamber is provided with a plurality of elongate slot nozzles extending transversely of the passage and the lower plenum chamber is provided with a plurality of elongate slot nozzles extending longitudinally of the passage, the nozzles directing heated air towards the articles from both above and below the articles in a criss-cross lattice pattern. Preand post-heat chambers are respectively located at the entrance and exit of the passage for gradually increasing and decreasing the temperature of the articles to prevent thermal shock.

This invention relates in general to heat exchange apparatus, and in particular to apparatus of the type that may, for example, be used to heat-shrink plastic film about packages and the like.

Present practice with respect to the heat shrinking of plastic film generally is to direct very hot high speed turbulent air onto such film. This technique is inefficient, and corollarily costly, because it tends not to wet the film with hot air for heat exchange purposes, but rather limits the time during which hot air is in contact with such film; that is, the air, being high speed, tends to bounce otf and away from the film, whereby heat exchange is ineffective.-

The present invention remedies the defects of the prior art by providing a lattice of thermal planes, each of which is comprised of a steady stream of low speed hot air. Plastic film, for example, passed through the lattice is thoroughly wetted by the air and, hence, heat exchange is maximal, To provide the aforesaid lattice, a pair of spaced apart plenum chambers are employed. The chambers are provided with respective pluralities of opposing slots, and the slots of one chamber are angularly oriented, about a common imaginary axis between the chambers, with respect to the slots of the other chamber. Hot air directed into the chambers emerges from the respective slots of the chambers to envelope in bath-like manner anything between the chambers.

In a presently preferred form of the invention, the two plenum chambers are joined by interconnecting ducts, whereby hot air, forced by common blower apparatus directly into one chamber, nevertheless also gets forced into the other chamber via the ducts. To minimize heat loss, and thereby improve the efliciency of the apparatus, both plenum chambers and the blower apparatus are supported within an externally insulated bafiie compartment, with only the input to the blower apparatus and the plenum chamber slots opening deliberately into such compartment. In this way the exhausted, but still hot, air from the plenum chambers is recirculated around such chambers and back into the blower apparatus, whereby attendantly heat loss from the chambers to the compartment is minimal since the temperature gradient therebetween is itself minimal.

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A principal object of the invention is to provide improved apparatus for use in altering the temperature of an article or the like.

Another object of the invention is to provide apparatus for producing a lattice of thermal planes through which articles and the like may be passed for heat exchange purposes.-

Another object of the invention is to provide eflicient heat exchange apparatus, which apparatus utilizes at least one plenum chamber, having output nozzle means, and pump apparatus for applying thermally conditionable air into said chamber, said chamber and said pump apparatus being both so enclosed within a bafiie compartment that only the output nozzle means of the plenum chamber and the input to said pump open deliberately into the bafile compartment.

Another object of the invention is to provide apparatus for producing a lattice of thermal planes through which articles and the like may be passed for heat exchange purposes, which apparatus is provided with a vestibular section that is heated as a result of its proximity to said lattice, and whereby thermal shock to said articles and the like is minimized.

The invention will be described with reference to the figures, wherein:

FIG. 1 is a cutaway sectional view of apparatus embodying the invention,

FIG. 2 is a view of the apparatus of FIG. 1 taken substantially along line 2-2 thereof, and

FIG. 3 is a perspective view of a portion of the apparatus of FIG. 1.

The invention is described in relation to a heat shrink tunnel for heat-shrinking plastic film around packages which are automatically conveyed into and out of such apparatus.

Referring to the figures, a first plenum chamber 10 has a plurality of elongated slot nozzles 12, and contains therein heating coils 14. The coils 14, which are sup ported on electrically n-onconductive rods 16, are electrically energized by power supplied via a cable 18. A second plenum chamber 20, having elongated slot nozzles 22, is supported above the plenum chamber 10, in spaced apart relation therewith, by means of a pair of ducts 24, 26, thereby defining a passage between the chambers. The ducts 24, 26 open into both plenum chambers 10, 20 and the nozzles 12 and 22 of respectively the chambers 10 and 20 open into the passage and are preferably orthogonally arranged with respect to each other. That is, nozzles 12 in chamber 10 extend longitudinally of the passage and nozzles 22 in chamber 20 extend transversely of the passage.

Blowers 28, 30 direct air into the base of the plenum chamber 10 via respective orifices 32, 34 and, because of back pressures within the chamber 10 resulting from the constrictive nozzles 12, air is forced from the chamber 10 to the chamber 20 via ducts 24, 26. The impellers 28a and 30a of respectively the pumps 28 and 30 are supported on a common shaft 36 which is pulley-driven by means of a motor 38, and such shaft 36 is rotatably supported in a bracket 40. The pumps 28 and 30' and coils 14- constitute a means for supplying heated air to both of the plenum chambers.

A three-part baffie compartment 42 surrounds the pumps 28, 30 and both plenum chambers 10, 20, with the top part 42T of the bafiie compartment housing the plenum chambers 10, 20 and the bottom two parts 42B thereof housing respective pumps 28, 30. The baffle compartment top and bottom parts 42T and 42B are interconnected by ports 44, with the inputs 46 and 48 respectively of the pumps 28 and 30 opening into their respective baffle compartment parts 42B, and the elongated output nozzles 12 and 22 of the plenum chambers opening into the top part 42T of the bafile compartment.

Ingress to the baffle compartment 42 to the space or passage between the plenum chambers 10, 20, and egress from such compartment are respectively via sectioned curtains 50, 52, which may for example be of rubberized material. An open conveyor 54, consisting of spaced apart rollers 56 that interconnect a pair of parallel chain linkages 58, constitutes a means for conveying articles and the like into the baffle compartment 42 and through the passage between the plenum chambers. Each chain linkage 58 meshes with a pair of sprockets 60 on respective shafts 62 and such, shafts are rotatably supported by the frame 64; the conveyer is driven by a motor 66 that chain-drives one of the shafts 62. The conveyer is designed in this fashion, ie with through-openings among its plural parts, in order to permit the free flow of air within the region between the plenum chambers 10, 20.

Hot air that leaks from the baffle compartment 42, eg via the sectioned curtains 50, 52, is trapped at least to some extent, within anteand post compartments 68, 70. This is an important aspect of the instant apparatus not only because it works to economize on the heat required of the apparatus, but more importantly because it affords compartments for gradually heating and cooling the articles being conveyed, whereby thermal shock to such articles is kept minimal. The ante or preheat compartment 68 has an entrance sectioned curtain 72 and the post or postheat compartment 70 has an exit sectioned curtain 74. The frame 64 preferably is so designed that it has external shoulder-like limbs 76, '78 on which articles may rest as they are conveyed into and out of the apparatus of the invention.

In operation, an article to be 'heated is placed on the conveyer 54 in the region of the shoulder-like limb 76. The conveyer 54 carries the article on its rollers 56 through the curtain 72 and into the ante-compartment 68, wherein the temperature of the article is gradually raised to an intermediate temperature by heat lost from the battle compartment 42, After traversing the ante-compartment 68, the article passes through the curtain 50 and enters the passage between the plenum chambers 10, 20 where a criss-cross lattice pattern of heated air impinges upon the articles. As the conveyer 54 carries the articles through the curtain 52, the article enters a region (post-compartment 70) of gradual cooling, ie. down from the cam-paratively high temperatures of the baffle compartment 42, after which time it ex-its on the conveyer through the curtain 74.

While the invention has been described in its preferred embodiment, it is to be understood that the words which have been used are words of description rather than of limitation, and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects.

Having thus set forth the nature of the invention, What is claimed herein is:

1. Heat exchange apparatus comprising first and second spaced plenum chambers defining a passage therebetween, each of said chambers having a plurality of elongate slot nozzles, the nozzles in the first chamber opening into said passage and extending longitudinally thereof and the nozzles in said second chamber opening into said passage and extending transversely thereof, means for supplying heated air to 'both of said plenum chambers, and means for conveying articles through the passage between the chambers, said conveying means comprising an open conveyor for permitting substantially free flow of air therethrough, whereby a criss-cross lattice pattern of heated air from said nozzles impinges upon the articles as they are conveyed through said passage.

2. The apparatus of claim 1 including a preheat compartment: the ingress region of said bafile means and a postheat compartment substantially enclosing the egress region of said bafile means, whereby the temperature of the articles as gradually increased and decreased prior to entering and after leaving said baflle means, respectively, thus preventing thermal shock.

References Cited UNITED STATES PATENTS 3,070,901 1/1963 Allander et al. 34160XR 1,910,868 5/1933 Webb 34-225 XR 2,677,336 5/1954 Spooner 34-225 XR 2,906,627 9/1959 Payton et al 53184 XR 3,175,565 3/1965 Dawson 34-216XR 3,222,800 12/1965 S'iegel et a1. 53-184 XR 3,226,839 1/1966 Monaghan 34-225 XR 3,309,835 3/1967 Peppler 53-184 XR FREDERICK L. MATTESON, IR., Primary Examiner.

JAMES W. WESTHAVER, Examinier.

A. -D. HERRMANN, Assistant Examiner. 

